Table of Contents
Definition of Bone Marrow Transplant
Typically the preparation process for the bone marrow removes T-cells and sometimes other leukocytes (white blood cells) to lower the likelihood of antigen response in the recipient. Common reasons for bone marrow transplantation include
- Some types of leukemia
- Some types of lymphoma
- Severe aplastic anemia
- Some other cancers that have not responded to first line treatments
Bone marrow transplantation is a complex and fairly high-risk procedure because the recipient’s native bone marrow must first be destroyed, which wipes out the body’s immune response capability.
Doctors accomplish this through high-dose chemotherapy or radiation therapy. After this preparation, the recipient must remain in protective isolation in the hospital to limit exposure to pathogens such as viruses and bacteria.
The transplant recipient receives the bone marrow blood stem cells, tissue-matched for compatibility between donor and recipient, via infusion into an intravenous line, much like receiving a blood transfusion.
The transplanted blood stem cells migrate to the bone marrow where they establish themselves (a process called engraftment). The migration and engraftment takes about three to four weeks, after which the transplanted blood stem cells begin producing new blood cells.
The immune functions of the bone marrow and blood cells begins to return in about six months, though is not complete for as long as two years. During this replenishment stage the person remains especially vulnerable to infection. As well, some people take immunosuppressive therapy to reduce the risk for rejecting the transplanted blood stem cells. Immunosuppression further limits the immune response.
Risks of Allogeneic Bone Marrow Transplantation
The primary risks of allogeneic (volunteer donor) bone marrow transplantation are infection and, with allogeneic donation, rejection of the transplanted blood stem cells.
There is no risk for rejection with autologous donation. Infection, however, can erupt at any time and has high risk for serious or fatal consequences for as long as the person’s immune response cannot provide protection. Early intervention with antibiotic medications can head off or reduce the severity of many bacterial infections.
Frequent blood tests monitor the return of healthy blood cells to the circulation. The success of bone marrow transplantation is highly variable and depends on numerous factors, including the kind of cancer and the general health of the person aside from the cancer. When successful, bone marrow transplantation can put the cancer into extended and sometimes permanent remission.